Aspects of the synapses and circuitry in the retinal plexiform layers of various vertebrates and invertebrates will be studied by 1) light microscopy of Golgi-impregnated tissue; 2) electron microscopy of tissue fixed by standard methods; and 3) a combination of the two, i.e. electron microscopy of Golgi-impregnated tissue. Major projects underway include: 1) studies of the inner plexiform layer of the ground squirrel and cat retinas in normal and visually deprived animals; and 2) detailed investigations of the photoreceptor synapses in gecko and rat retinas.